How to Grind and Use a Flat Bottom Drill

[@AstroHoff]

Exactly what I needed. No BS, just easy to follow demonstration. Thanks.

[@marcelf21953]

I built one of these about 27 years ago to recess a washer and bolt head below flush. This video is bringing back memories of that metal fabrication job.

[@TomsTechniques]

Thanks for watching

[@rescobar8572]

I'm striving to be as knowledgeable as yourself. Thanks Tom!

[@worthdoss8043]

Been hand sharpening my own bits for many years and this made me fell like an idiot for not thinking of it.:>) I just went out and gave it a try in some steel plate on my drill press it worked great. Thanks.

[@TomsTechniques]

Thanks for watching, WD.

[@kirkpennock2997]

I have a set of black cheap drills I don't use any more, this is going to be the new thing they are for, thanks.

[@rensfunhog]

I am so glad you published this... I had a situation working on my vintage triumph and needed to clean a counter-bored hole that had an aluminum washer mashed into it. I tried picking at it - but took a step back and figured I needed some sort of flat drill bit, but for metal. Searched Internet and 'boom' your KZbin post caught my eye. I used my dewalt handheld grinder and carved out a 1/2" flat bit. It reamed out that aluminum washer and any other junk at the bottom of this hole - now i'm ready to put it back together with a good seal on this end. Saved me some $$... Thanks...

[@TomsTechniques]

I love success stories! Thanks for watching, Tom

[@c0mputer]

Awesome, thanks for this. I'm going to try my hand at this in the morning. I was researching machine shops in my area to do a countersink for some Allen cap screws, but now it looks like I can do it on my own!

[@idsubgun]

Great video! I was going to describe how to make a flat bottom drill in a post on a gun forum, and thought I'll look and see if a video has been made. I ran across this video and shared it. I'm retired now but was a tool & die machinist for over 35 years, and a gunsmith for 24 of those years. I started watching some of your other videos and see you've been in front of a manual mill and lathe for some time too! Great videos!! I subscribed! Thanks !!

[@TomsTechniques]

+Bill P. Thanks. I did have a CNC mill at my disposal for ten years or so at my last job and miss it a lot. I hope to purchase one for myself in the near future. But yes, a lot of time on manual mills over the last 40 years. Never used a CNC lathe. Tom

[@532bluepeter1]

Dear Tom, Thank you for posting this video. I had always believed that this was the province of the D bit but this looks as if it will cut faster and in a more balanced fashion: this I must try. I also had a nightmare at the weekend trying to drill brass with freshly honed drill bits and having watched your video on sharpening for brass I understand why I was having problems as my drills would have had blunter lips previously. Thank you very much; I shall be purchasing two sets of drill bits to modify accordingly for future use. I very much enjoy that you come quickly to the point and that you do not allow your ego to get in the way of the information. Your consideration of the viewer is much appreciated.

[@TomsTechniques]

Thanks Jack

[@keithnoneya]

Nice Tom, had to do this for work one day. They ordered a part, waited a year and a half for it then the part was wrong. Boss knew I had a mill at home and asked me to make him one. Made him two done in a few hours, customer finally happy.

[@TomsTechniques]

+Keith Noneya Thanks Keith. It's always nice to be able to make your own tools. Tom

[@joemmams5785]

I know it's an old video but it's still very much appreciated...thanks

[@TomsTechniques]

Old, but hopefully still useful. Thanks for watching.

[@mrblack61]

When ever im looking on something on youtube, I know im gonna get a result when one Toms videos pops up in the search. cheers mate ;)

[@CJacquot]

Well its 2018 and your video is still helping people. Thanks. Now I dont gotta go ask my boss to help me haha

[@dalemcinnes1834]

Well it's 2022 and it's still helping people. I have made and used them but nice to see Tom's take on them. I save any broken bit to make them and usually works out good. Dale in Canada 🇨🇦

[@77Avadon77]

Flat bottom drills you make the Rockin world go round 🎤🎼🎵🎶

[@oerllikon2]

Thank you, needed this for a bushing

[@TomsTechniques]

You are very welcome.

[@petedetects7012]

I think that was great video. lf the relief angles are made identically like an endmill could that same flat bottom drill bit you made cut like an endmill . If taking little 1/8" passes at a time . Have you ever attempted that .Thanks for the video. Big Mex

[@TomsTechniques]

Thanks. Drill bits have no relief on the flutes, so they won't cut sideways like an end mill. They are also not stiff enough for side milling.

[@TomsTechniques]

Thanks Denis. A set of flat bottom drills is a useful tool to have that doesn't cost much to acquire.

[@donmoore7785]

Great video - exactly what I was hoping to learn to do.

[@aaronholstrom1971]

Thanks for the video Tom. I really appreciate you sharing your knowledge.

[@TomsTechniques]

My pleasure Aaron

[@denisl2406]

your right about the cost and we always have doubles and triples of drill bits laying around in the tool chest. im starting a set asap! although i have lots of end mills i never have the one that fits the hole im drilling,so there we go problem solved. thanks again. Denis

[@gilelicyd]

Thank you Tom yet again for a great tip. I shall watch all your video's as they not only instructive but also entertaining.

[@TomsTechniques]

A little entertainment always helps with the learning process. Thanks for watching! Tom

[@robert5]

End mills do work for this also, if it is a standard size. If the end mill is not center cutting I drill a tiny bit deeper so there is a clearance dimple in the center of the hole so I don't have to worry about the center cutting part but still end up with the square bottom as needed. I have also used end mills to drill through holes to final size using endmills. Just did it with a 3/8" mostly because my good 3/8 drill bit chipped a flute so I just drilled it the next size under and used a nice sharp 3/8 endmill to get final size. It left a super nice finished hole that was very close to exact .375. Over all drill bits are usually cheaper then end mills so I don't do this much.

[@TomsTechniques]

Thanks David. It's the same site, I just renamed it to Tom's Techniques because I'm setting up a machining web site in that name and I wanted to eliminate any confusion between here and there. Tom

[@not_riley]

thank you for making this instructional video. Very helpful

[@arkansas1313]

I've got to get started on making a set of flat bottom drills. All my broken bits will nearly complete a set. Thanks for sharing the tip....13

[@newstart49]

A good way to use short broken old bits instead of tossing them. Thanks.

[@TomsTechniques]

Maybe. The web gets thicker as the bit gets shorter, so at some point, it won't be worthwhile.

[@dalemcinnes1834]

@@TomsTechniques I've found with a predrilled hole it usually works okay. It is fairly easy to make the web smaller then anyway. Dale in Canada 🇨🇦

[@MrNigel1340]

Very helpfull videos thank you, what was the material you used to dress the grinding wheel with please.

[@TomsTechniques]

+Doc Cox Thanks. Those are silicon carbide dressing sticks. You can get them at any industrial supply, such as McMaster Carr. Tom

[@MrNigel1340]

Thanks Tom, have found them on Ebay.

[@snakedike]

That's a good trick. I have a CNC so I generally interpolate flat bottom holes. But this would come in very handy when the diameter is small or the hole is deep. Thanks

[@TomsTechniques]

...or if you are using a drill press. Thanks for watching.

[@byarnneil1916]

Helped Me out, thanks for sharing.

[@TomsTechniques]

Good to hear. Thanks for watching.

[@tricklidz]

Ill look for one. Thanks for the quick reply. You vids Rock!!

[@TomsTechniques]

Thanks Steve.

[@edgeeffect]

Reminds me of the song "Flat bottom drills, you make the rockin' world go round"

[@TomsTechniques]

Lol

[@graemebrumfitt6668]

Great vid Tom, TFS "thanks for sharing" have a few old bits I'm gonna do this with! G :)

[@gt1749v]

Great video. 👍👍👍😊

[@norwamoom]

Thanks Tom, I need to make some of these.

[@TomsTechniques]

They are handy to have on hand.

[@75Bird455]

Good stuff - still working on perfecting the sharpening of 118° bits, will move on to this afterwards, thanks!

[@FJandG]

Tom, another great video, thanks. Learning a lot from these. A bit hard to see what you did on the closeups as it was out of focus but I think I see what you did.

[@TheJesusno2]

WOW! That was great! never though about that one! thanks gotta check out the sheetmetal one now!

[@lestertapaya4263]

I should have watched u first before i make a counterbore 😂 From Philippines.

[@TomsTechniques]

Thanks. It's definitely worthwhile to make up a set of at least the common sizes. Tom

[@Stepapajon2]

Brilliant as always.

[@kentvandervelden]

Pretty slick tip

[@driftmunkey]

Great video, exactly what Im looking for except I need a flat #41 and dont have the time to order one.

[@dumpy4289]

thanks excellent & concise!

[@resipsaloquitur13]

Excellent.

[@mirsadmemic5863]

That sharpening stone is the best way to sharpening grinding wheel. But need good experience. When you got that you will like them a lot.

[@tomc5560]

Thanks for this!

[@matthiasschulze393]

just the help i needed thanks

[@TomsTechniques]

+Matthias Schulze It's good to hear that the videos are being used. Thanks for watching. Tom

[@tricklidz]

Little off the subject but what was the stone you used to "dress" the grinding wheel?

[@TomsTechniques]

It's just a dressing stick. They create a smoother surface than the star wheel type of dresser. Any industrial supply will carry them. Tom

[@62346]

Tom, Will this site replace the other? Thanks for the Vid!...always useful. BTW focus is out. Dave

[@TomsTechniques]

Absolutely. They will cut anything a regular twist drill will cut as long as the rpm is correct for the material.

[@mukerjea]

Hi, Thanks for the informative video. I need a little help from you. I am into Railroad hobby and do it in N scale. My need is to make a hole of diameter of 16mm x 80mm deep hole in to the soft metal chassis. Can you advice how to do it? Thanks in advance.

[@TomsTechniques]

Ashis Mukerjea A 16mm x 80mm hole in an N scale chassis??? That sounds bigger than the entire chassis. Any size flat bottom hole can be made by drilling the hole to depth (including the point) and then making the bottom flat with a drill like I made in the video. Tom

[@mukerjea]

thanks

[@cigarcaptain]

I can use this tip, thanks Tom

[@TomsTechniques]

Glad you can use it and thanks for watching. Tom

[@randymcsmash]

Another useful video, thanks Tom. I think it would be cool if you had cut two holes with the drill, put a flat bottom in only one of them; then sectioned the block through the holes to show the difference between the two holes. (It wouldn't really add anything to the instructional value of the video I guess.)

[@jefffrankart5136]

From, thanks for the great videos. I have two questions about this one. 1. Could you use the flat bottomed drill to drill the entire depth of the hole? 2. When do you use the dressing stick on the grinder compared to the spur style dressing wheel?

[@TomsTechniques]

1) No. A flat bottom drill will wander severely if it isn't pilot drilled first. 2) Dressing sticks are good for fine dressing, like forming a radius on the corner of the wheel. Star dressers are better for dressing the face of the wheel. Thanks for watching Jeff. Tom

[@p4pTapouT]

I've found your drill bit sharpening video a while ago and also watched this one. Very well done. So today I tried to grind one (12mm) to drill stainless steel (4mm) because a regularly ground drill produced a triangular hole - nothing new. Mine probably wasn't as perfect as yours but I think it was close enough. What I experienced is that the cutting edges got pretty mangled. After about four holes the edges were flat and not that peaked anymore. Did I do something wrong or is it just the fact that it's stainless steel? Need the version for stainless steel to be ground differently? Rpm was suitable and I cooled.

[@TomsTechniques]

A 12mm drill in stainless should be run at about 400 rpm or slower. Even a little faster will toast a drill in stainless. Also make sure that you have adequate clearance so the drill doesn't rub behind the cutting edge and heat up. Tom

[@p4pTapouT]

Toms Techniques Thank you for the answer, Tom. I've just noticed I've replied to the wrong video :/. Of course I meant the sheet metal drills. Sorry! Yeah, I drilled at about 200 rpm. So that shouldn't have been a problem. I modified it a little bit today. I've ground it almost like a flat bottom drill but kept the little pilot. It actually worked very well. I've drilled about 130 holes today and didn't need to sharpen once. It still looks good :) Maybe the sharp, thin cutting edge like in your sheet metal drill video isn't made to last when drilling stainless? Have you tried drilling stainless with your sheet metal drills? If your cutting edges last, I clearly made a mistake when grinding mine the first time.

[@caemaridwn]

Thanks for the tip Great idea :)

[@TomsTechniques]

Thanks for watching!

[@roberttibbetts6743]

Great video. You make it look so easy! I just tried making a flat bottom 3.5 mm drill. This is a lot smaller than the one you demonstrated, ans also I am a machining newbie, so I found it a bit tricky - in particular, grinding up to, but not past, the flattened edge. But I thought that if you go a tiny bit past, it should be OK to then re-flatten the end (just enough to get the edge back). Is this technique valid? The drill sort of worked, but only if I drilled with a pointed one first). Would it be better to use a split-point drill? Would a pointed drill still have to be used first? Cheers, Bob (UK)

[@TomsTechniques]

Hi Bob, Flat bottom drill bits are only intended to flatten the bottom of a pre-drilled hole. They will not drill a hole by themselves. It's best to avoid leaving a flat on the cutting edge because it will prevent the drill from cutting, but it does take a bit of practice to get the depth right. If you blacken the edge with a marker before grinding, it will be easier to see. Tom

[@roberttibbetts6743]

@@TomsTechniques OK, thanks very much Tom

[@milkman447]

Hi Tom. I really like your videos--lots of good tips here. One question: I've noticed you always drill at what looks to be high spindle speeds. I've always used the rule of thumb that drilling speeds should be ~1/3 the cutting speed for the same diameter end mill. Can you comment on this? Thanks!

[@TomsTechniques]

+drotar447 I've actually never heard that, nor can I think of a good reason for it. About the only thing I run slower than an end mill are reamers to reduce heat, because they don't clear chips very well and taps for better control. Drills run at full speed. Thanks for watching. Tom

[@mcskifter]

drotar447 unless your tools are different materials, there is no reason not to run them at the same surface speed.

[@Tadesan]

Beautiful

[@delron44]

nice tip, thanks .

[@denisl2406]

thats a good idea thanks tom. Denis

[@helicrashproprocrasher2367]

Could you just drill the hole with the flat bottom drill? I'm sure it would not work as well as a normal drill but how well would it work?

[@TomsTechniques]

+helicrashpro procrasher No. The drill will walk all over the place without a point. You need to drill it nearly to depth with a regular drill then finish up with a flat bottom. Tom

[@TAknifeChannel]

Could I make a flat bottom with a square end mill? How accurate is this method?

[@TomsTechniques]

End mills will work if a hole is drilled first, but using an end mill alone will result in an oversize hole. Tom

[@boltonky]

Plain, simple brillant

[@TomsTechniques]

I'm plain and simple, but I don't know about brilliant. :) Thanks for watching.

[@leoouellette3835]

Thank you.

[@kennedysingh3916]

Thank you, I have a simuler hole to drill I a steel block.

[@jakesako]

Thanks for the reply , regards jake

[@jakesako]

Hi , do they cut mild and stainless steels without problems ?

[@ugotit33x]

EXCELLENT THANK YOU

[@goober650NX]

I like that. 👍

[@TomsTechniques]

Pretty handy

[@TomsTechniques]

Thanks, glad you enjoyed it.

[@yucholkim5276]

Flat bottom girl you make the rock and roll go around...

[@dracobushcraft3523]

What I am looking at doing is knife scales for a folding knife. The requirement is a hole through the scale with a flat bottom counter sink. I don't have a mill (though I do have one of the little metal lathes). I do have a drill press as well. So how do I countersink with a flat bottom? It seems like it would be hard to line up in my drill press. Being a flat bottom and sucn a small hole what are my options?

[@TomsTechniques]

You have to drill the hole first, then use a piloted counter-bore for the flat bottom hole. You can buy them for different sized screws. Just set the depth stop on your drill press to suit. Tom

[@dracobushcraft3523]

Thanks Tom. Google came up with several sources.

[@spraynpray]

Step 1: Spend three hours getting your belt sander to a 90 degree angle. Step 2: Sand bit flat Step 3: Cut clearances Got it! I wish step 1 was easy.

[@TomsTechniques]

It's too easy for a part that's angled up to grab the joint on a belt sander and dig in. That's why I prefer to grind clearances on a wheel. Tom

[@spraynpray]

Toms Techniques Absolutely. Grinding the clearances on a belt would be very difficult.

[@TomsTechniques]

It's not the focus. KZbin publishes the video long before the processing is complete. The quality will improve over the next couple of days. Tom

[@faw3511]

Have a care with that belt sander. That tool is deadly. Watching made my toes curl.

[@TomsTechniques]

I take care with any power tool I use. The fact that I make it look so easy comes from the amount of experience I have using them.

[@karlphilipp93]

you basically just made a 2 flute end mill

[@TomsTechniques]

Not quite. A 2 flute end mill is side cutting, drills are end cutting.

[@62346]

Maybe wrong here.......I thought Griffin was in the site name!!

[@damojfowler]

Or just use an end mill.

[@TomsTechniques]

Drills are available in many more sizes than end mills and they don't require a mill to use, since unlike drills, they are side cutting. Tom

[@ErikAdalbertvanNagel]

Cool. But you can actually buy one.

[@TomsTechniques]

Or you can repurpose old drills and not have to buy one.

[@romaineathey3663]

I think you can learn more about it on woodprix website.

[@yurakovalec7292]

This time I will do it manually with the help of Woodglut designs.

[@danielguerrero4336]

I know it just aluminum, but don't show guy pulling shavings with there bare hands.

[@TomsTechniques]

I guess if someone tries it with steel and gets cut, they'll know to be more careful next time.

[@Tadesan]

6:05 2 seconds doing the work. The work isn’t what you are paying for!!!

[@ericwarren7719]

Stupid simple.... in 15 years that has never occurred me, usely use a end mill... 🙄

[@rescobar8572]

I'm striving to be as knowledgeable as yourself. Thanks Tom!

[@newstart49]

+Rolando Escobar You can say that again! LOL.

[@rescobar8572]

I'm striving to be as knowledgeable as yourself. Thanks Tom!